Conventionally, there is a workpiece pick-up device which captures an image of a plurality of workpieces piled up in a container by a sensor from an upper side to obtain three-dimensional information in which detected points respectively have height information, and determines that the highest portion of the three-dimensional information is a position where a workpiece to be picked up next is located, and picks up the workpiece which is located at the position by a robot. (See PTL 1, for example.)